docs: def get_src_ids(sources):
      """
      :returns:
         a string with the source IDs of the given sources, stripping the
         extension after the colon, if any
      """
      src_ids = []
      for src in sources:
          long_src_id = src.source_id
          try:
              src_id, ext = long_src_id.rsplit(':', 1)
          except ValueError:
              src_id = long_src_id
          src_ids.append(src_id)
      return ' '.join(set(src_ids))